Applications of Alternating Current/Alternating Potential Electro­lysis in Organic Synthesis

Abstract

This review summarises the rarely used method of alternating current electrolysis for the synthesis of organic products. Different waveforms have been investigated which opens the possibility for further influence the outcome of the electrolysis by variation of the frequency as well as the highest peak current. In recent years alternating current electrolysis has been applied in increasingly more complex transformations. Especially the functionalisation of (hetero)arenes, functional group manipulation, metathesis reactions, and transition-metal-catalysed cross-coupling reactions were reported in recent years and the results of these and some other investigations are summarized in this review article.1 Introduction1.1 Waveforms1.2 Objectives1.3 Early Examples of the Optimisation of Alternating Current Electrolysis2 Recent Applications of Alternating Current Electrolysis for Organic Synthesis2.1 Substitution Reaction on Arenes2.2 Nitrogen–Sulfur Bond Formation and Sulfur–Sulfur Bond Metathesis2.3 Oxidation and Reduction2.4 Cross-Coupling Reactions2.5 Frequency Optimisation3 Conclusion

Overcoming the Potential Window-Limited Functional Group Compatibility by Alternating Current Electrolysis

“…In recent years, alternating current (AC) electrolysis has become a powerful synthetic tool because of its unique oscillating redox environment. − For instance, we recently demonstrated using AC frequency to control the α-amine functionalization selectivity and hydrogen isotope exchange at α-C­( sp 3 )-H amine sites . Other groups have used AC electrolysis to overcome undesired reductive metal deposition for silver-catalyzed C–H phosphorylation, control chemoselectivity of carbonyl compounds reduction and heteroarene electroreduction, selective synthesis of 4-alkoxy anilines via a formal CO/OH cross-metathesis, and to minimize overoxidation/reduction in unsymmetrical disulfide synthesis …”

Stirring‐Free Scalable Electrosynthesis Enabled by Alternating Current

“…An elegant solution may arise from the principle of alternating current (AC) electrolysis, a flexible tool for mild and selective organic transformations [15–21] . The increasing interest in AC electrolysis is largely due to its demonstrated benefits in redox‐neutral processes, where the periodic switch of electrode polarity provides a unique approach for interelectrode mass transfer [22–28] .…”

“…An elegant solution may arise from the principle of alternating current (AC) electrolysis, a flexible tool for mild and selective organic transformations. [15][16][17][18][19][20][21] The increasing interest in AC electrolysis is largely due to its demonstrated benefits in redox-neutral processes, where the periodic switch of electrode polarity provides a unique approach for interelectrode mass transfer. [22][23][24][25][26][27][28] This feature may serve as the foundation for an alternative reactor design, where AC, combined with diffusiondriven mass transfer, enables uniform electrolysis across the whole volume of the reactor, filled with a fine net of 3D electrodes (Figure 1C).…”

Alternating Current Electrolysis for Individual Synthesis of Methanol and Ethane from Methane in a Thermo-electrochemical Cell

“…Other advantages of AC electrolysis over direct-current (DC) electrolysis have been reviewed by Luo et al . and Hilt et al We also previously demonstrated an additional effect of AC electrolysis: the ability to control the oxidizability of active oxygen by optimizing the frequency for the oxidation of benzene to phenol …”

“…24 and C−H phosphorylation reactions, 25 respectively. Other advantages of AC electrolysis over directcurrent (DC) electrolysis have been reviewed by Luo et al 26 and Hilt et al 27 We also previously demonstrated an additional effect of AC electrolysis: the ability to control the oxidizability of active oxygen by optimizing the frequency for the oxidation of benzene to phenol. 28 The objectives of the present study were (1) to assess the electrocatalytic activity of Pt or various metal-added Pt anodes, (2) to observe the dependence of the voltage, temperature, flow rate, and the presence/absence of water vapor on the production of methanol and ethane, (3) to compare the DC and AC electrolysis methods for continuously synthesizing methanol and ethane, and (4) to deduce the optimal parameters such as the waveform and frequency for the AC electrolysis.…”